The matching law states that the absolute amount of each form of behavior is proportional to the relative amount of reinforcement associated with it. While the law has been confirmed, at least approximately, in numerous experiments, the procedures used have, for the most part, been similar. The main objective of the work proposed is to test the limits of generality of the law, by examining different drives, different forms of responding, and different configurations of association between behavior and its consequences. We believe the matching law to be the correct quantitative form of the law of effect, which is to say that we believe that the law of effect is a principle of motivation, rather than learning. Consequently, a secondary objective is to begin to examine the ties between the matching law and the learning processes involved in both the elicitation of behavior and the formation of simple concepts or percepts.